1. Field of the Invention
The present invention relates to a magnetic disc apparatus, a head positioning mechanism and a mobile information device provided with a magnetic disc apparatus.
2. Description of the Prior Art
In the conventional magnetic disc apparatus, there is provided with a lock mechanism for fixing a head as disclosed in Japanese Unexamined Patent Publication No. 7-130119 in order to improve a reliability with respect to an impact applied thereto at a non-operated time. On the contrary, with respect to a vibration and an impact applied from an external portion during recording and reproducing operations, in order to prevent data from being broken and being erroneously read due to the reason why the position of the head is shifted from a track, there are given a function of stopping the recording and reproducing operation when a shock sensor provided on a circuit board of the disc apparatus detects an impact and a function of monitoring a head position error signal for controlling the positioning so as to stop the recording operation when an amount of shift of the head from a center of the track becomes large.
Conventionally, a voice coil motor is generally used for an actuator moving a head positioning mechanism in the magnetic disc apparatus. The voice coil motor is excellent in response, however, has a problem that the voice coil motor is sensitive to the vibration and the impact applied from the external portion. For example, when an impact in a rotational direction is applied to the disc apparatus from the external portion, an acceleration in a rotational direction is generated in the head positioning mechanism corresponding to a movable portion relatively with respect to a disc apparatus casing and a disc. However, since the movable portion is not restricted in a rotational direction, an acceleration applied to the casing from the external portion becomes an acceleration for rotating the head positioning mechanism with respect to the casing. The acceleration generates a position shift from a target position of the head.
Accordingly, the magnetic disc apparatus is provided with a function of interrupting the recording and reproducing operation of the data when detecting a vibration and an impact or detecting a large position shift. Therefore, under existence of the vibration and the impact, a throughput of the magnetic disc apparatus is deteriorated. In the case that the applied vibration and impact are great, the date break is caused. Accordingly, the head position shift applied to the vibration and the impact from the external portion is a great obstruction in view of realizing a high throughput and a high reliability of the disc apparatus. In particular, in a product which is used under a state that the vibration and the impact always exist, such as a mobile information terminal, a on-vehicle information device or the like, there has been a problem that a sufficient performance can not be obtained.
An object of the present invention is to provide a disc apparatus provided with an actuator in which a position shift of a head is not generated even under a vibration and an impact applied from an external portion, and a mobile information device having a high throughput and a high reliability given by the magnetic disc apparatus.
In order to achieve the object mentioned above, the present invention is characterized in that a head positioning mechanism for moving a head to a target radial position on a disc is constituted by a coarse actuator and a fine actuator, the coarse actuator is used at a time of moving between the tracks so as to perform a positioning operation, and the fine actuator is used with keeping a position of a movable portion of the coarse actuator without performing a feedback servo control at a time of following the track so as to perform a positioning operation.
In accordance with a first aspect of the present invention, there is provided a magnetic disc apparatus comprising:
a recording medium in which a track constituted by a set of data is formed on a recording surface;
a recording and reproducing element recording and reproducing the data on the track;
a head supporting mechanism supporting a head provided with the recording and reproducing element; and
an actuator constituted by a movable portion connected to the head supporting mechanism and a stationary portion fixed to a casing,
wherein the magnetic disc apparatus is provided with a holding mechanism for holding the movable portion of the actuator driving the head supporting mechanism at a fixed position while an input command value is constant.
In accordance with a second aspect of the present invention, there is provided a magnetic disc apparatus as recited in the first aspect, wherein the holding mechanism brings a member fixed to the casing side into contact with the movable portion so as to keep a position of the actuator at an optional position.
In accordance with a third aspect of the present invention, there is provided a magnetic disc apparatus as recited in the first aspect, wherein the holding mechanism has two the actuators and is structured such that the respective actuators apply a drive force in a direction of keeping the head supporting mechanism at a fixed position.
In accordance with a forth aspect of the present invention, there is provided a magnetic disc apparatus as recited in the third aspect, wherein the actuator has a plurality of teeth and grooves in a stationary element side and is provided with a coil having teeth and grooves in such a manner as to oppose to the stationary element and applying an electric current.
In accordance with a fifth aspect of the present invention, there is provided a magnetic disc apparatus as recited in the first aspect, wherein the actuator is a coarse moving actuator largely moving the head supporting mechanism at a high speed, and a fine moving actuator finely moving the head so as to position is provided in the head supporting mechanism.
In accordance with a sixth aspect of the present invention, there is provided a magnetic disc apparatus as recited in the second aspect, wherein the actuator is a coarse moving actuator largely moving the head supporting mechanism at a high speed, and a fine moving actuator finely moving the head so as to position is provided in the head supporting mechanism.
In accordance with a seventh aspect of the present invention, there is provided a mobile information device provided with a magnetic disc apparatus comprising:
a recording medium in which a track constituted by a set of data is formed on a recording surface;
a recording and reproducing element recording and reproducing the data on the track;
a head supporting mechanism supporting a head provided with the recording and reproducing element; and
an actuator constituted by a movable portion connected to the head supporting mechanism and a stationary portion fixed to a casing,
wherein the movable portion of the actuator driving the head supporting mechanism is held at a fixed position while an input command value is constant.
In accordance with an eighth aspect of the present invention, there is provided a magnetic disc apparatus comprising:
a magnetic disc provided with a recording surface for recording data;
a magnetic head moving on the recording surface so as to record and reproduce the data;
a magnetic head supporting mechanism supporting the magnetic head; and
a coarse moving actuator connected to the magnetic head supporting mechanism and positioning the magnetic head to a predetermined position,
wherein the actuator is provided with two drive portions for driving the magnetic head supporting mechanism in a rotational direction and a reverse-rotational direction of the magnetic disc, the drive portion is constituted by a stationary element fixed to a casing of the disc apparatus and provided with a plurality of teeth and a movable element provided in a magnetic head supporting mechanism side and having a plurality of teeth so as to oppose to the teeth of the stationary element, and the magnetic head supporting mechanism is moved and held at a fixed position by applying a predetermined voltage to the movable element.